This collaborative program is conducted by Riverside Research Institute (RRI) and the Columbia University College of Physicians and Surgeons (CUCPS). The goal of the program is to establish quantitative ultrasonic means for objectively diagnosing and monitoring diseases of the liver, pancreas and kidney. The program applies computer processing to radio-frequency (rf) echo signals from conventional ultrasonic scanners. A number of acoustic parameters are computed using spectrum analysis, with calibration procedures to remove system artifacts. As shown in our theoretical analyses, these parameters sense microstructural features such as the size, shape, concentration, and mechanical properties (density and compressibility) of internal tissue scatterers, even those too small to be resolved in ultrasonic images. Disease-indexed data bases are established using these parameters together with ancillary data, including biopsy results. Data-base studies are showing how this multi-parameter approach can be used to diagnose focal and diffuse diseases in abdominal organs. To refine these methods, we are including intraoperative as well as trans- abdominal clinical scans. We are also emphasizing the use of parameter images and "staining" to indicate the spatial distribution of characteristic parameter values. New parameters are being included to characterize tissue heterogeneity and to obtain absolute estimates of tissue properties unaffected by attenuation in intervening tissue. New acoustic microscopy procedures are also being combined with analytic investigations to provide insights that will help refine our characterization procedures and interpretation strategies.